Heat-proof electric wire having a benzimidazole-based polymer coating

Abstract

An insulating material comprised of a benzimidazole-based polymer layer and a fluorine-containing rubber layer. This material is heat-resistant and is especially useful for use in electric wires. To manufacture such wires, a varnish solution is prepared by dissolving partially polymerized benzimidazole-based polymers in a solvent, then adding a polymerization initiator thereto. Subsequently, an electric wire is soaked in the solution and heated to cross-link the benzimidazole-based polymers. By repeating this procedure, the electric wire is coated with any desired thickness of a benzimidazole-based polymer layer. This coated wire is further coated with a fluorine-containing rubber layer to obtain a heat-resistant electric wire that is also resistant to dielectric breakdown.

What we claim is: 
     
       1. A heat-resistant insulating material for an element including at least one electrically conductive part, said material consisting essentially of a first layer comprising at least one first polymer based on at least one benzimidazole monomer, said layer having an internal surface, and an external surface facing away from said internal surface; and   a second and outermost layer comprising at least one second polymer derived from at least one fluorine-containing monomer, said second layer being adhered to said external face of said first layer.   
     
     
       2. The insulating material of claim 1 wherein said first layer comprises a plurality of polymer layers, including an inner layer and an outer layer, said internal surface being on said inner layer and said external surface being on said outer layer. 
     
     
       3. The insulating material of claim 1 wherein said internal surface is in contact with said element. 
     
     
       4. The insulating material of claim 1 wherein there is an insulating layer between said element and said internal surface. 
     
     
       5. The insulating material of claim 1 wherein said first polymer is according to Formula I ##STR3## wherein x is an integer of at least 5 and is selected so that said first polymer is solvent soluble. 
     
     
       6. The insulating material of claim 1 wherein said fluorine-containing monomer is selected from the group consisting of a, b, c, and mixtures thereof ##STR4## wherein l, m, and n individually indicate a total number of monomers a, b, and c, respectively, in said second polymer, each of l, m, and n bring an integer between 20 and 200,000, R 1  to R 4 , R 1  ' to R 4  ', and R 1  " to R 4  " being individually hydrogen, fluorine, chlorine, substituted or unsubstituted methyl, or O--R 5 , wherein R 5  is hydrogen, alkyl having 1 to 12 carbon atoms, cyclohexyl, cyclohexyl substituted by at least one alkyl having 1 to 4 carbon atoms, hydroxy alkyl having 1 to 8 carbon atoms, aminoalkyl having 1 to 8 carbon atoms, dialkylaminoalkyl having 1 to 8 carbon atoms, glycidyl, tetrahydrofuran, tetrahydrofuran substituted by at least one alkyl having 1 to 4 carbon atoms, benzyl, (--CH 2  CH 2  --O--) t  CH 2  CH 2  OH wherein t is an integer between 1 and 10, and R 6  --N--R 7  wherein each of R 6  and R 7  is hydrogen or alkyl having 1 to 4 carbon atoms, at least one of R 1  to R 4 , R 1  ' to R 4  ', and R 1  " to R 4  " in said second polymer is fluorine. 
     
     
       7. The insulating material of claim 2 wherein said fluorine-containing monomer is selected from the group consisting of a, b, c, and mixtures thereof ##STR5## wherein l, m, and n individually indicate a total number of monomers a, b, and c, respectively, in said second polymer, each of l, m, and n bring an integer between 20 and 200,000, R 1  to R 4 , R 1  ' to R 4  ', and R 1  " to R 4  " being individually hydrogen, fluorine, chlorine, substituted or unsubstituted methyl, or O--R 5 , wherein R 5  is hydrogen, alkyl having 1 to 12 carbon atoms, cyclohexyl, cyclohexyl substituted by at least one alkyl having 1 to 4 carbon atoms, hydroxy alkyl having 1 to 8 carbon atoms, aminoalkyl having 1 to 8 carbon atoms, dialkylaminoalkyl having 1 to 8 carbon atoms, glycidyl, tetrahydrofuran, tetrahydrofuran substituted by at least one alkyl having 1 to 4 carbon atoms, benzyl, (--CH 2  CH 2  --O--) t  CH 2  CH 2  OH wherein t is an integer between 1 and 10, and R 6  --N--R 7  wherein each of R 6  and R 7  is hydrogen or alkyl having 1 to 4 carbon atoms, at least one of R 1  to R 4 , to R 1  ' to R 4  ', and R 1  " to R 4  " in said second polymer is fluorine.